A related question I have had is: can you transfer communities you have created to another instance? I’m sure the answer is no.
I’ve been very happy with lemmy.world, but I will be stopping my donations and finding another instance if it federates with Threads.
Nothing. They will exist as long as the instance exists.
You can appoint a new mod yourself before leaving, or your own account from a different instance. But if you are the only mod when you delete the account then yes. Instance admins can still apoint someone else though.
How do you appoint new mods though? I don’t see a menu to moderate the communities I created.
They will likely disappear.